Solar Cell and Method for Manufacturing the Same

Abstract

A highly reliable solar cell is achieved which has a high photoelectric conversion efficiency and no aged deterioration. A cell 10 (unit cell) is formed as a unit, comprising: a lower electrode layer 2 (Mo electrode layer) formed on a substrate 1 (substrate); an absorber layer 3 (CIGS absorber layer) which contains copper, indium, gallium, and selenide; a highly resistant buffer layer thin film 4 formed of InS, ZnS, CdS, or the like on the absorber layer 3; and an upper electrode layer 5 (TCO) formed of ZnOAl or the like, and furthermore, a contact electrode section 6 for connecting between the upper electrode layer 5 and the lower electrode layer 2 is formed in order to connect a plurality of unit cells 10 in series. The contact electrode section 6 has, as will be explained later, a Cu/In ratio higher than that of the absorber layer 3, and in other words, has less In contained therein to have a property of p+ (plus) type or a conductor relative to the absorber layer 3 which is a p-type semiconductor.

1 . A solar cell, comprising:
 a substrate;   a plurality of lower electrodes which are formed by dividing a conductive layer on the substrate;   a chalcopyrite absorber layer which is formed on the plurality of lower electrodes and divided into a plurality of parts;   a plurality of upper electrodes which are transparent conductive layers formed on the absorber layer; and   a contact electrode section which is formed by modifying a part of the absorber layer for enhancing the conductivity thereof so that unit cells each of which is comprised of the lower electrodes, the absorber layer, and the upper electrodes ate connected in series.   
     
     
         2 . The solar cell according to  claim 1 , wherein
 the contact electrode section has a Cu/In ratio which is higher than that of the absorber layer.   
     
     
         3 . The solar cell according to  claim 1 , wherein
 the contact electrode section is an alloy which contains molybdenum.   
     
     
         4 . The solar cell according to any one of  claims 1  to  3 , wherein
 a buffer layer is formed between the absorber layer and the upper electrodes.   
     
     
         5 . A method for manufacturing a solar cell, comprising:
 a conductive layer forming step for forming a conductive layer as a lower electrode on a substrate;   a first scribing step for dividing the conductive layer into a plurality of lower electrodes;   an absorber layer forming step for forming a chalcopyrite absorber layer on the lower electrodes;   a contact electrode section forming step for enhancing the conductivity of a part of the absorber layer by radiating a laser beam on the part;   a transparent conductive layer forming step for forming a transparent conductive layer on the absorber layer and the contact electrode section as an upper electrode; and   a second scribing step for dividing the transparent conductive layer into a plurality of upper electrodes.   
     
     
         6 . The method for manufacturing a solar cell according to  claim 5 , the method further comprising a buffer layer forming step after the absorber layer forming step, wherein a laser beam is radiated on a formed buffer layer in the contact electrode section forming step.